/*
 * @lc app=leetcode.cn id=695 lang=cpp
 *
 * [695] 岛屿的最大面积
 *
 * https://leetcode.cn/problems/max-area-of-island/description/
 *
 * algorithms
 * Medium (67.65%)
 * Likes:    793
 * Dislikes: 0
 * Total Accepted:    210.2K
 * Total Submissions: 310.7K
 * Testcase Example:
 * '[[0,0,1,0,0,0,0,1,0,0,0,0,0],[0,0,0,0,0,0,0,1,1,1,0,0,0],[0,1,1,0,1,0,0,0,0,0,0,0,0],[0,1,0,0,1,1,0,0,1,0,1,0,0],[0,1,0,0,1,1,0,0,1,1,1,0,0],[0,0,0,0,0,0,0,0,0,0,1,0,0],[0,0,0,0,0,0,0,1,1,1,0,0,0],[0,0,0,0,0,0,0,1,1,0,0,0,0]]'
 *
 * 给你一个大小为 m x n 的二进制矩阵 grid 。
 *
 * 岛屿 是由一些相邻的 1 (代表土地) 构成的组合，这里的「相邻」要求两个 1 必须在 水平或者竖直的四个方向上 相邻。你可以假设 grid
 * 的四个边缘都被 0（代表水）包围着。
 *
 * 岛屿的面积是岛上值为 1 的单元格的数目。
 *
 * 计算并返回 grid 中最大的岛屿面积。如果没有岛屿，则返回面积为 0 。
 *
 *
 *
 * 示例 1：
 *
 *
 * 输入：grid =
 * [[0,0,1,0,0,0,0,1,0,0,0,0,0],[0,0,0,0,0,0,0,1,1,1,0,0,0],[0,1,1,0,1,0,0,0,0,0,0,0,0],[0,1,0,0,1,1,0,0,1,0,1,0,0],[0,1,0,0,1,1,0,0,1,1,1,0,0],[0,0,0,0,0,0,0,0,0,0,1,0,0],[0,0,0,0,0,0,0,1,1,1,0,0,0],[0,0,0,0,0,0,0,1,1,0,0,0,0]]
 * 输出：6
 * 解释：答案不应该是 11 ，因为岛屿只能包含水平或垂直这四个方向上的 1 。
 *
 *
 * 示例 2：
 *
 *
 * 输入：grid = [[0,0,0,0,0,0,0,0]]
 * 输出：0
 *
 *
 *
 *
 * 提示：
 *
 *
 * m == grid.length
 * n == grid[i].length
 * 1 <= m, n <= 50
 * grid[i][j] 为 0 或 1
 *
 *
 */

// @lc code=start
#include <iostream>
#include <vector>
using namespace std;
class Solution {
public:
    int maxAreaOfIsland(vector<vector<int>> &grid) {
        if (grid.empty() || grid[0].empty())
            return 0;
        int max_area = 0;
        for (int i = 0; i < grid.size(); ++i) {
            for (int j = 0; j < grid[0].size(); ++j) {
                max_area = max(max_area, dfs(grid, i, j));
            }
        }
        return max_area;
    }

    int dfs(vector<vector<int>> &grid, int r, int c) {
        if (r < 0 || r >= (int)grid.size() || c < 0 || c >= (int)grid[0].size() || grid[r][c] == 0) {
            return 0;
        }
        grid[r][c] = 0;
        return 1 + dfs(grid, r + 1, c) + dfs(grid, r - 1, c) + dfs(grid, r, c + 1) + dfs(grid, r, c - 1);
    }
};
// @lc code=end
